Fraunhofer Institute for Integrated Circuits IIS
Fraunhofer Institute for Integrated Circuits IIS
© Adobe Stock, Delphotostock

© Adobe Stock, Delphotostock

Satellite IoT paves the way for worldwide connectivity

Satellites can be used to transmit data all around the globe. They gather data for the Internet of Things (IoT) and relay them to well-connected ground stations, from where the data ultimately make their way to the user. To make things even easier, we are developing efficient transmission methods for IoT transmitters that send signals directly to the satellite from any location on Earth.

 

It is clear from the numerous applications that worldwide connectivity via the IoT has been a reality for some time. Many of these applications are tailored to life in the city, where sensors are used to monitor parking spaces or to measure environmental and weather data. At present, IoT networks therefore tend to emerge at well-connected locations, typically in major urban centers. Low-power wide-area networks (LPWANs) feature energy-efficient transmitters and a range of about 15 kilometers and are therefore ideally suited to smart city applications. The networks needed here consist of a large number of objects that transmit their sensor data to a central IoT base station. From there, the data are relayed via mobile communications or DSL so that they can be accessed over the Internet at any time.

Satellites are growth accelerators for the IoT

What is easy to do in a city becomes a genuine challenge in the most remote regions of the planet, given the lack of communication infrastructure. Out on the ocean, deep in the jungle, or in the desert or the Arctic, there is simply no infrastructure for feeding data into the Internet. This can be remedied by using satellites to establish a communication network with global availability and to relay data to distant ground stations that are connected to the Internet.

These satellite-based IoT applications, which are currently in operation, use an LPWAN with an IoT base station to first receive and bundle data from sensors over a wide area before sending them to a satellite. As a result, collecting IoT data at very remote locations is no longer a problem – albeit only if the network is limited to a specific area. For example, a farm could install a single, central base station with a satellite link in order to monitor a wide range of machinery as well as the animal population and environmental and soil parameters. After all, satellite connectivity allows the IoT to reach even the most remote locations.

IoT transmitters send signals directly to the satellite

Another problem arises, however, as soon as there is movement involved, such as when determining the position of vehicles moving around within a larger radius. Although the range of traditional LPWAN solutions is large, it is not unlimited. To allow uninterrupted monitoring of a vehicle fleet, the vehicles must never lose their connection to an IoT base station, however, it is extremely costly to build a seamless network of this kind – especially in remote regions and when relatively few objects need to be connected.

We have therefore developed a solution in which the IoT objects no longer require a fixed base station, but rather transmit data directly to the satellite. The only requirements for this are an IoT transmitter designed for satellite operation and a suitable transmission method. Theore- tically, any device can therefore transmit data directly to the satellite, allowing an unlimited range of movement for IoT devices.

The transmission method for transporting data from the mobile transmitter to the satellite is based on our well-established MIOTY® LPWAN technology, which is in turn based on a standard issued by the European Telecommunications Standards Institute (ETSI). In the method known as telegram splitting, the transmitter divides every message up into smaller packages and sends them at different frequencies in staggered transmissions. As only about 50 percent of the packages need to reach the receiver for the message to be unscrambled, this method is extremely robust against interference factors and allows transmissions by a large number of sensors at the same time. We have tailored the transmission method especially to satellite communications so that signals can cover the distance to the satellite in space.

 

»THE INTERNET OF THINGS TRAVELS AROUND THE WORLD BY SATELLITE.«

 

Satellite constellations provide seamless coverage

The special thing about our satellite IoT solution is its easy implementation. It can be incor- porated into existing commercially available chipsets, allowing transmitters to be developed and produced cost-efficiently. Moreover, the transmission method is so energy-efficient that even small batteries can supply the IoT transmitters with the necessary power for a prolonged period of time. To increase battery life further, our transmitters can also be extended with solar cells or other energy harvesting techniques.

Once the transmitters are in operation, they are almost maintenance-free and can be used with satellite constellations in low Earth orbit (LEO) over a period of years – for example, to record and relay environmental and positioning data. These LEO satellites travel around Earth at high speed and in large constellations with several satellites per orbit. This guarantees that a satellite is always available to receive the data from the transmitters and to transport them to the nearest base station. For example, forest fires or leaks in oil pipelines can therefore be detected and brought under control at an early stage.